Syntheses of fluoro-oxindole and 2-fluoro-2-arylacetic acid derivatives from diethyl 2-fluoromalonate ester

Diethyl 2-fluoromalonate ester is utilised as a building block for the synthesis of 2-fluoro-2-arylacetic acid and fluorooxindole derivatives by a strategy involving nucleophilic aromatic substitution reactions with ortho-fluoronitrobenzene substrates followed by decarboxylation, esterification and reductive cyclisation processes

Conductance behavior of tetraphenyl-Aza-Bodipys

We studied the electrical conductance of single-molecule junctions formed from molecular wires with four anchor groups. Three tetraphenyl-aza-BODIPYs with four or two thiomethyl anchor groups were synthesized, and their single-molecule conductance was measured using break-junction-STM. Using DFT based calculations these compounds were shown to display a combination of a high and low conductance, depending on the molecule's connectivity in the junction. A scissor correction is employed to obtain the corrected HOMO-LUMO gaps and a tight binding model (TBM) is used to highlight the role of transport through the pi system of the tetraphenyl-aza-BODIPY central unit. The three higher-conductance geometries follow the sequence 3 > 4 > 2, which demonstrates that their conductances are correlated with the number of anchors

Low-melting molecular complexes: Part VII. 2,3-, 2,5- and 3,4-hexanediones and their molecular complexes with chloroform

Crystals of three isomeric 2,3-, 2,5- and 3,4-hexanediones 1–3 and of molecular complexes (1:2) of 2 and 3 with chloroform (4 and 5) were grown by in situ cryocrystallisation and characterised by single-crystal X-ray crystallography. The intermolecular interactions and packing motifs were examined using the analysis of pairwise energies of intermolecular interactions. The method has revealed the importance of carbonyl…carbonyl interactions in the structures 1, 3 and 4 and the relatively weaker halogen bonds in the structures 4 and 5

Polymorphism of non-linear optical material N-(4-nitrophenyl)-N-methylamino-acetonitrile (NPAN)

Two new crystalline polymorph modifications of the non-linear optical material N-(4-nitrophenyl)-N-methylamino-acetonitrile (NPAN) have been found and their structures have been established by X-ray analysis. The low-temperature structure of previously known polymorph of NPAN has also been determined. The comparative analysis of the packing of the NPAN molecules in these polymorphs provides the hints to the process of crystallization of the NPAN in different conditions

N,N-diethyl-5-nitropyridin-2-amine.

In the title compound, C9H13N3O2, the asymmetric unit contains two almost identical but crystallographically independent mol­ecules. The mol­ecules are linked together by pairs of weak C-H...O inter­actions into zigzag chains, which, in turn, form corrugated layers perpendicular to the a axis

Synthesis, Ni(II) Schiff base complexation and structural analysis of fluorinated analogs of the ligand (S)-2-[N-(N′-benzylprolyl)amino]benzophenone (BPB)

Herein we report the first X-ray crystal structure of the well-known (S)-l-ala-Ni-BPB complex (1) and compare this with the X-ray crystal structures obtained for two novel fluorinated (S)-l-ala-Ni-BPB complexes (8 and 12) that contain either an S- or R-fluorine atom on the proline ring of the BPB ligand. The preparation of complexes 8 and 12 has been enabled by the synthesis of two new fluorinated BPB ligands (7 and 11). In this work we looked to observe the structural effects that the introduction of a single fluorine atom had on the known complex 1. Arising from this, we highlight a novel fluorine–nickel interaction that on the basis of DFT calculations appears to provide additional stabilization to one of the complexes prepared ((S)-l-ala-Ni-BPB complex 8)

A family of readily synthesised phosphorescent platinum(II) complexes based on tridentate N^N^O-coordinating Schiff-base ligands

The synthesis and photophysical properties of 22 platinum(II) complexes featuring N^N^O-coordinating ligands are described. The complexes have the form Pt(N^N^O-Ln)Cl (n = 1 to 20). The tridentate ligands comprise lateral pyridine and phenolate rings, offering the metal N and O coordination respectively, linked via an imine or hydrazone unit that provides a further, central N atom for coordination. The proligands HLn, some of which have previously been reported for the coordination of 1st row transition metal ions in other contexts, are Schiff bases that are readily synthesised by condensation of salicylaldehydes either with 8-aminoquinoline (to generate imine-based ligands HL1–4) or with 2-hydrazinopyridines (to generate hydrazone-based proligands HL5–20). The Pt(II) complexes are prepared under mild conditions upon treatment of the proligands with simple Pt(II) salts. Metathesis of the chloride ligand by an acetylide is possible, as exemplified by the preparation of two further complexes of the form Pt(N^N^O-Ln)(–C[triple bond, length as m-dash]C–Ar), where Ar = 3,5-bis(trifluoromethyl)phenyl. Nine of the complexes have been characterised in the solid state by X-ray diffraction. The imine-based complexes have intense low-energy absorption bands around 520 nm attributed to charge-transfer transitions. They display deep red phosphorescence in solution at ambient temperature, with λmax in the range 635–735 nm, quantum yields up to 4.6% and lifetimes in the microsecond range. The hydrazone complexes that feature a py–NH–N[double bond, length as m-dash]C–Ar linker display pH-dependent absorption spectra owing to the acidity of the hydrazone NH: these complexes have poor photostability in solution. In contrast, their N-methylated analogues (i.e., py–NMe–N[double bond, length as m-dash]C–Ar) show no evidence of photodecomposition. They are phosphorescent in solution at room temperature in the 600–640 nm region, the emission maximum being influenced by substituents in the phenolate ring. The results show how simply prepared tridentate Schiff base ligands – which offer the metal a combination of 5- and 6-membered chelate rings – can provide access to phosphorescent Pt(II) complexes that have superior emissive properties to those of terpyridines, for example

Tetrahydropyrido 3,4-b pyrazine scaffolds from pentafluoropyridine

Representative polyfunctional tetrahydropyrido[3,4-b]pyrazine scaffolds have been synthesized very readily by a one-pot annelation reaction of pentafluoropyridine with appropriate diamines. The trifluorinated pyridopyrazine products react sequentially with various nucleophiles to give polysubstituted tetrahydropyridopyrazines, demonstrating the potential of the polyfluorinated ring fused pyridine system as a scaffold for the synthesis of previously inaccessible polysubstituted pyridopyrazine derivatives. This general approach has special relevance to the development of new chemical entities for the life science industries and particularly in the drug discovery arena, in which low molecular weight, polyfunctional heterocyclic derivatives are playing an increasingly important role